As defined in the Honor manual, plagiarism is "the act of using someone else's words or ideas as your own without giving proper credit to the source." Here are some resources to aid in the writing process as well as to help with citing your sources.
The Citadel's Writing Center resources page includes different topics from "The Writer's Toolbox" and links to other useful writing-related websites.
http://citadel.edu/wlcenter/ 
The Merriam-Webster online dictionary and thesaurus (the URL may be shortened to "m-w.com").
http://www.m-w.com/dictionary.htm
APA's online guide to writing style.
http://www.apastyle.org/
MLA's online guide to writing style.
http://www.mla.org/
Bartleby.com offers a basic writing guide, a description of elements of writing style, and a discussion of various writing-related issues.
http://www.bartleby.com
The Grammar Handbook at the Writers' Workshop (University of Illinois at Urbana-Champaign) is helpful at answering basic questions about grammar, including questions about nouns, verbs, adjectives and adverbs, conjunctions, and other parts of speech.
http://www.english.uiuc.edu/cws/wworkshop/grammar_handbook.htm
The Bibliography Styles Handbook at the Writers' Workshop (University of Illinois at Urbana-Champaign) is a guide to both the APA and MLA styles of bibliography.
http://www.english.uiuc.edu/cws/wworkshop/bibliography.htm
The Writers' Workshop (University of Illinois at Urbana-Champaign) offers answers to grammar questions, tips on writing, online critiques, and more.
http://www.english.uiuc.edu/cws/wworkshop/index.htm
The Writers' Workshop (University of Illinois at Urbana-Champaign) has a resource page designed for foreign students that have learned English as a second language.
http://www.english.uiuc.edu/cws/wworkshop/eslresources.htm
Bedford/St. Martin's offers a quick guide to online sources and citations.
http://www.bedfordstmartins.com/online/index.html
Roget's online thesaurus.
http://humanities.uchicago.edu/orgs/ARTFL/forms_unrest/ROGET.html
